In MongoDB, the $isoDayOfWeek aggregation pipeline operator returns the weekday number in ISO 8601 format, ranging from 1 (for Monday) to 7 (for Sunday).
You can optionally specify a timezone to use for the result.
The $isoDayOfWeek operator accepts either a date (as either a Date, a Timestamp, or an ObjectId), or a document that specifies the date and timezone to use.
In MongoDB, the $dayOfWeek aggregation pipeline operator returns the day of the week for a date as a number between 1 (Sunday) and 7 (Saturday).
You can optionally specify a timezone to use for the result.
The $dayOfWeek operator accepts either a date (as either a Date, a Timestamp, or an ObjectId), or a document that specifies the date and timezone to use.
In MongoDB, the $dayOfMonth aggregation pipeline operator returns the day of the month for a date as a number between 1 and 31.
You can optionally specify a timezone to use for the result.
The $dayOfMonth operator accepts either a date (as either a Date, a Timestamp, or an ObjectId), or a document that specifies the date and timezone to use.
In MongoDB, the $dayOfYear aggregation pipeline operator returns the day of the year for a date as a number between 1 and 366.
You can optionally specify a timezone to use for the result.
The $dayOfYear operator accepts either a date (as either a Date, a Timestamp, or an ObjectId), or a document that specifies the date and timezone to use.
I thought it would be interesting to run a few quick queries to see how various formatting strings affect the formatting of date/time values.
In PostgreSQL, you can use the to_char() function to return dates in various formats.
One of the things you can do with this function is return the month portion of a date in roman numerals.
Continue readingIn PostgreSQL you can use the extract() function to get the week number from a date.
You can also use the date_part() function to do the same thing.
In PostgreSQL, you can use the to_char() function to get the short day name from a date.
By “short day name” I mean the abbreviated day name, for example Fri, Mon, etc.
The to_char() function accepts two parameters; the date and the format string with which to format that date.
In PostgreSQL you can use the extract() function to get the day from a date.
You can also use date_part() to do the same thing.
When extracting the day from a date, you need to specify what sense of the word “day” you mean. For example, “day of week”, “day of month”, “day of year”, etc.
Here are two ways to convert a given Julian day to its date value in PostgreSQL.
The first method directly inputs the Julian day into the date data type.
The second method uses the to_date() function to return the same result.
Julian day is the number of days since Monday, January 1, 4713 BC using the proleptic Julian calendar, which is November 24, 4714 BC, in the proleptic Gregorian calendar.
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